nibbled fins

This is a discussion on nibbled fins within the Beginner Freshwater Aquarium forums, part of the Freshwater Fish and Aquariums category; -->
Hi all
we've just started adding fish to the new 28g bowfront. We ran it for two day with just the filter to settle ...

Hi all
we've just started adding fish to the new 28g bowfront. We ran it for two day with just the filter to settle everything out and with a pair of little used filters from our two Betta tanks. Then I bought 3 live plants and added them. Next day we moved over the two little mosquito fish. I also bought a planted driftwood that had been in the lfs tank for about a year so it should have lots of good bacteria on it. I took out the extra filters. So far up to this point ammonia, Nitrite and Nitrate were all running 0.
We went back to one lfs and bought 3 zebra Danio and 3 long finned leopard Danio and 6 cherry shrimp. Within a few hours all three zebra Danio were floating belly up so we flushed them. Ammonia, nitrite, nitrate still 0. We had noticed that they were just staying at the surface the whole time before they died. Next day we went to a different store (Petsmart) and bought 4 more long finned leopard Danios thinking to keep to one type rather than mixing. These seemed a bit larger and less brightly colored but we hoped they would school together.
Nobody has gone belly up but I notice that three or four of them have chomped tail fins. Everyone is zipping around the tank, including the 2 mosquito fish. It's hard to tell if any ones are chasing the others but it seems like the original smaller ones are the ones with the chomped fins.
Today the ammonia is between 0 and 0.25 but nitrite and nitrate are still 0.
The cherry shrimp are all hiding - we don't get much sight of them any more.
Is there anything we can do about the fin chomping when they are all (except the two mosquitos) the same species of fish but from two different sources? Will their fins grow back?

In a week or two we plan on adding 4 cory cats. Then will come 6 rasboras and 1 Dwarf Gourami.

mush, you hit the nail on the head! That's exactly what it sounds like from here, also. As for the fin nipping, that is common when something like danios don't have enough decorations and/or plants in the tank for hiding places. The smaller fish will usually always get picked on. Try floating some plants in the tank, since these fish prefer to be near the surface. With plastic plants you can snap off the clear plastic piece at the bottom and float them, or you can work with something like hornwort, which is a live plant and rather easy to grow, especially when floating.
What kind of test kits are you using? As for adding more fish, watch the water params, and let them tell you when the tank is ready for more fish. Some tanks take longer to cycle than others.
If you keep feedings light, what the fish can finish in 1 - 2 minutes and only every other day, then you should be pretty good. Don't add the corys or other fish until your ammonia and nitrite are both at zero and there is some kind of nitrate reading showing up. If you add them before the tank is fully cycled, you'll likely kill them, and possibly the other fish, too.

mush, you hit the nail on the head! That's exactly what it sounds like from here, also. As for the fin nipping, that is common when something like danios don't have enough decorations and/or plants in the tank for hiding places. The smaller fish will usually always get picked on. Try floating some plants in the tank, since these fish prefer to be near the surface. With plastic plants you can snap off the clear plastic piece at the bottom and float them, or you can work with something like hornwort, which is a live plant and rather easy to grow, especially when floating.
What kind of test kits are you using? As for adding more fish, watch the water params, and let them tell you when the tank is ready for more fish. Some tanks take longer to cycle than others.
If you keep feedings light, what the fish can finish in 1 - 2 minutes and only every other day, then you should be pretty good. Don't add the corys or other fish until your ammonia and nitrite are both at zero and there is some kind of nitrate reading showing up. If you add them before the tank is fully cycled, you'll likely kill them, and possibly the other fish, too.
What kind of filter are you running? What is your temp? You might find you need to add an air stone to increase oxygen levels and circulation in the tank.

from the original fish added only 3 of six died. They were all the zebras. The Leopards bought from a different tank at that same store are all fine and zipping around.

My filter was the one with the o ring sticking out of the connection. We got it put back in but I worried that because it was pinched it would leak so I bought a Penguin Bio Wheel 150 rated for 30 gallons. I have a 100 watt heater and the temp in the tank is around 76-78 or so. I am using a dechlorinator with stress stuff in it. I will have to look to see the brand name though. The tank had water in it for at least 4 days before we added the fish though so the Cl should have dissapated. I can add an air stone (darn - those little pumps are noisy!) and some floating plants too.

The test kit is the liquid AP type. I just got a liquid pH kit and it is 7.6 is this too high?

Plants will eat some of the nutrient level, but not all of it, which is why we still need to do water changes. Plants also put out waste of their own if any part of them dies (such as a leaf floating at the surface or trapped between decorations).
For the 3 of 6 to die, chances are that those fish had a weaker immune system, were smaller, or some other vulnerability to the conditions in your tank. If the cause was due to oxygen loss, those most vulnerable to it would die first... which would increase the oxygen levels in the tank (less fish using it).

In order to rely on plants to help "filter" your tank, you are talking about using A LOT of plants with just a FEW fish.
I am wondering, how often is your light left on? Plants produce oxygen, but they also use oxygen, and therefore need enough light AND enough dark to function properly. If there is not enough circulation in the tank, and temps are warmer, then at night, there could be a problem in balance of oxygen levels. Warmer water has less oxygen, at night plants use oxygen, as do the fish. Did the fish die during the night?
(this is simply one possibility, and without being able to examine the fish after they died and without being able to run tests and observe the situation in person, this would be difficult to impossible to pinpoint a "for sure" cause of death)

no, it seemed like the fish were sick/weak to begin with. We floated the bags for about 20 minutes for the temp to equilibrate then netted the fish out of the bags and into the tank. The three zebras stayed at the top the entire time, never really swimming around whereas the leopards took off exploring and zipping around. They (the zebras) were dead within a few hours.
We turn the lights off around 9 pm or so and on at around 7 am or so. I will be upgrading the bulb in the hood to a brighter "floral" type to give the plants more light soon as I realized I chose bright light requirement plants.
I will look into adding an airstone and some floating plants.

The zebra danios were all very small, and upon inspection, their stomach cavities seemed to be very sucked into their bodies, rather than the typical bow of a fish form. Perhaps they were sick when we got them, being new again to the hobby we may have neglected the signs of a weak or sick fish at the time of purchase. We have 7 long-finned leopard danios, 3 that were purchases at the same time from the same lfs that the zebras were purchased from, and four additional ones from another store we visited a few days later. With the exception of the nipped fins, they are very active and seem very healthy. I added a dose of Stress Zyme as directed on the bottle to help them heal their fins. It seems the smaller ones we purchased first are more the aggressor, as they tend to chase the larger, newer leopards around quite a bit. And the female mosquito is less of a bully, as she now gets chased by the smaller leopards. I think the nipping is coming from leopards on leopards. The two mosquito fish have undamaged fins.

That sounds like a typical leopard danio behavior, especially if there is lack of territory where they need it.
Once again I will suggest adding some kind of floating decorations to break up the territory in the upper 1/2 of your tank. The smaller ones were there first, they chose their territory, and then you added "intruders". They are only defending what they see as theirs. With additional territory, they should calm down with the nipping, but the territory they need broken up is at the surface, not down below where the current plants are situated.